Control for fluid operated motors



Jan. 16; 1945. 1', STACY 2,367,241

' CONTROL FOR-FLUID OPERATED MOTORS Filed March 18,- 1959 5 Sheets-Sheet1 RESERVO/E Jan. 16, 1945. F, STACY O. I 2,367,241

CONTROL FOR FLUID OPERATED MOTORS 'Filed March 18, 195 3 Sheets-Sheet s35 .35

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' ATTORNEYS Patented Jan. 16, 1945 UNITED STATE CONTROL FOR FLUIDOPERATED MOTORS Thomas F. Stain? Piqua, Ohio, assignor to The chineryCompany, Piqua,

French Oil Mill Ma Ohio Application March 18, 1939, Serial No. 262,709

9 Claims. (01. 60-52) This invention relates to fluid operated motorssuch as hydraulic presses, and more particularly to a hydraulic circuitand control means therefor. It, is in the nature of an improvement uponthe subject matter disclosed and claimed in my copending application.Serial No. 204,375 filed April 26,1938, now Patent No. 2,335,809, datedNovember 30, 1943. 4 One object of the invention is to provide animproved hydraulic system and control means In the embodiment of theinvention illustrated in Fig. 1 the fluid actuated motorincludes a ramor fluid actuated motors, which may be successfully applied to varioustypes of fluid operated motors in'cluding the standard, high speed,selfcontained, hydraulic press, with automatic reversing means eitherwhen a predetermined pressure on the work has been reached or theworking member vof the motor has reached a predetermined position in itstravel, and which will be relatively smooth, efiicient. and dependablein operation, and relatively simple, compact and inexpensive.

' Another object of the invention is to provide an improved operatingsystem and control for hydraulic presses and the like, with which rapidoperation of the press in both directions will be possible/with whichthe' advance travel of the working member or ram may be terminated bymanual control or automatically, with which objectionable shocks in thesystem will be prevented, and which will be exceptionally free fromoperating troubles. I

Other objects and advantages will appear from the following descriptionof some embodimentsof the invention, and the novel features will beparticularly pointed out hereinafter in connection with the appendedclaims.

In the accompanying drawings:

Fig. 1 is a schematic diagram of portions of a fluid actuated motorhaving thecontrol of the; hydraulic system therefor constructed andarranged in accordance with this invention;

element or working member I having a piston 2 reciprocating in a ramcasing 3, with a mam cylinder 4 at one side of the piston to force theram element forwardly in a working stroke anda pullback cylinder 5 atthe opposite side of the piston 2 for retracting the ram element I fromthe work. These parts are typical of fluid actuated motors such as areemployed in hydraulic presses, for example. In many cases the pullbackcylinder is in a separate housing from the main cylinder 3. butconnected to the ram element or working member I, and it will beunderstood that the'ram elementor working member is actuated vin onedirection by pressure in the main cylinder and in the opposite orretracting direction by gravity or a pullback cylinder, whether the mainand pullback cylinders operate'on the same or different pistonsconnected to the working member].

Anysource of operating fluid underpressure may be employed, but thesource is, preferably a pump 6 which draws liquid from a suitablereservoir 1 through a passage-8 and delivers it under pressure through apipe 9. Any suitable type of pump may be employed, the oneillustratedbeing cf the variable displacement or variable delivery Fig. 2 is aschematic diagram of a portion of the same system and controls shown inFig; 1,

but illustrating a slight modification thereof;

Fig. 3 is a schematic diagram of a portion of the system of Fig. 1 andshowing another slight type, in which any slippage of liquidvis'returned by pipe I0 .to the reservoir 1. A light pressure the pump 6and the main controlling br operating valve l2. This valve II is set toopen on a predetermined light pressure, and thus it operates as a chokevalve to provide a sufiicient back pressure for a purpose which willappear presently. The valve l2 includes a casing for a valve chamber l3,in which reciprocates a valve element M. The valve element M is providedwith a pair of spaced lands I 5 and I6 which are of a size to fitclosely with the wall of the chamber I3 and cooperate with ports in thewallet chamber l 3 in a manner which will be described presently.

A helical compression spring I1 is compressed between one of thelands-,such as l6, and an end wall It of thel'lousing l2, and'urges thevalve element It in a downward direction (Fig. 1). The pipe 9 opens intothe valve chamber l3 through a port l9 which is located between thelands l5 and I6 when the valve element It is in an intermediateposition, which is the position shown by full lines in Fig. 1. A pipe 20opens into the valve chamber l 3 through a port aligned with the land 16when the valve element is in said intermediate position, and also isconnected to the main cylinder 4. Another pipe 22 opens into the chamber[3 through a port 23 which is aligned with the land l when the valveelement I4 is in its said intermediate position. The land I5 is of awidth which normally closes this port 23, so as to close communicationto that end of the pipe 22. It will be understood that the ports l9, 2|and 23 may be annular grooves in the wall of the chamber l3, into whichgrooves the pipes open.

The land I5 is bevelled on opposite faces at theperiphery thereof, asshown in Fig. 1, so that when it is aligned with the port 2| there willbeclearance between the land and the sidesof the port 2|, and fluid inthe chamber [3 received through the port l9 and pipe 9 may pass throughport 2| around the land l5 tothe upper end of the chamber l3, as. wellas pass to the pipe 20.

An exhaust pipe 24 opens into the upper end of the chamber l3 through aport 25,. and in turn is connected to the pipe [0 leading back to thereservoir 1. The lower end of thechamber l3 also has a port 25 openinginto the pipe 24.

The pipe 22' is connected to the pullback cylinder v 5. A pipe 21 leadsfrom the reservoir 1 to the cylinder 4 and it contains in seriesthereina pilot operated, free check valve 25. This check valve opensfreely to pass liquid from the reservoir 1 to the main cylinder 4 butnormally closes automatically to prevent all reverse flow.

The reservoir I should preferably be elevated abovethecylinder 4 tofacilitate free flowof oil or liquid from the reservoir into thecylinder during the prefill portion of the movement of the ram orworking member I, or else the liquid in the reservoir 1 may be under airor other .similar pressure. When fluid pressure supplied to'the pilotcylinder 29, however, it forces the pilot piston upwardly or outwardlyagainst the action of the pilot spring 3|, so as to engage and forceopen the 'movable free valve. element 32 of the check valve 28, and thusallow fluid to flow from the cylinder .4 through the pipe 21 back to thereservoir I. The pilot cylinder 23 is connected by a pipe 33 to-the pipe22 which leads to the pullback cylinder 5.

The valve element |4 extends outwardly through one end of the valvehousing I2, and this projecting end has two annular flanges 34 and 35spaced apart. Between these flanges is disposed a forked end35 of alever 31, which is and lower the piston 44 in the chamber 42, or inother words to withdraw it from contact with an end of the valve elementl4.

The press is also provided with an auxiliary valve casing 5| having achamber 52 therein in which' reciprocates a valve element 53. The valveelement 53 extends through both ends of the casing 5|, suitable packingglands bein Provided in the end walls through which the valve elementextends. The portion of the valve element within the chamber 52 isprovided with two lands-54 and 55 which are arranged in spaced relationto one another along the chamber 52. A helical spring 51 is compressedbetween the upper part of the chamber 52 and the land 54, so as tonormally urge the valve element 53 downwardly. The lower end of thevalve element 53 depends through a slot or aperture 58 provided in alaterally extending arm of the platen 59 which is carried by the workingmember or ram This element 53 carries an adjustable collar 50 at a pointabove the platen 59,'so that as the platen 59 is elevated during aretraction, it will pick up the collar 55 and shift the valve element 53,upwardly against the action of spring 51'. It is shown in its upperposition in Fig. 1. A pipe 5| connects the pipe 25, leading to the mainthe lands 54-and 55 when the valve element 53 is in its elevatedposition shown in Fig. 1. An-

pivoted at 38 and urged into a neutral or intermediate position by twooppositely disposed springs 39. The free end of the lever 31 has ahandle 4|) by which it may be operated in either or both directions.

The lower end of the valve element l4 passes through a packing 4| andinto a chamber 42.

. ilange or head 45. A rod 41 extends from the head 45 outwardly throughthe bottom of the chamber 45, through a packing 48 in said bottom wall,and exteriorly of the chamber 45 carries an adjustable abutment 49 whichmay be a pair of nuts threaded onto the rod, and one acting as a locknut for the other. A helical compression spring 50 compressed betweenthe nuts 45 other'pipe 55 leads from the chamber 52 between the lands 54and 55, but close to the land 55, when the-valve element 53 is in itselevated position and at its other-end is connected to the chamber 45 inthe lower part of the housing of the valve 2. 1

The port 54 is at apoint substantially above the opening into pipe 55 sothat when the valve element 53 is released by the platen 59 and moveddownwardly by the spring 51, the land 54 will cover-or pass port 54 andinterrupt communication between pipes 53 and 55. It will be noted thatwhen the valve element 53 is in 'the position shown in Fig. 1, which isits elevated position, the chamber 45 of the main control valve ber 52and pipes 53 and 22 with the pullback chamber 5. when the valve element53 is released and is moved downwardly by its spring 51, thiscommunication of the chamber 45 with the pullback chamber of the ramwill be broken by land 54 covering port 54, and since the land 55 willthen be below the port 52, the pipe 55 from the chamber 45 will then bein communication with the pipe 5| leading to the pipe 20 and the mainchamber 4.

An auxiliary or activities control valve 55 is provided with areciprocating valve element 5'! which has portions of the same diameterextending through opposite ends of its housing, so as to be a balancedvalve. Within the chamber 58 of this valve, the valve element 51 is provided with spaced lands 5!! and 10 of equal diameters or face areas. Apipe 1| opens at one end into the chamber 42 and at its other endthrough a port 12 into the chamber 58 of this activities control valve55. Another pipe 13 opensinto the chamber 68 of the same valve throughthe When the valve element 61 is in the position shown by full lines inFig. 1, the land will be between the ports 12 and 14, so that the fluiddelivered by thepump through the pipes 9 and I3 and entering the chamber68 will be confined in the chamber 88 by the lands 69 and "hand byreason of the fact that the lands 69 and 10 are the same size, suchpressure between those lands will-be balanced and will not urge thevalve element 81 in either direction. Since the port 12 will-be in freecommunication, through the chamber as, with the port 15, the chamber 42will be in communicationwith the reservoir; and there will be no fluidunder pressure in chamber 42.' When the valve element 61 .is in itsdotted line position shown in Fig. 1, the land 10 will be disposedbetween the ports Y72 and I5,

' and the land 69 will stay between the ports 14 and 16.

In that situation, the communication between is in the dotted lineposition of Fig. 1, the fluid under pressure from the pump 9 and passingthrough valve 66 not only serves to shift the valve element i4 upwardlyinto the position in which the land I6 is between the ports 21' and toinitiate a forward or working movement of the ram l, but it also holdsthe valve element l4 hydraulically in that active position with thespring I! compressed. It now the valve element 81 is returned to thefull line position of Fig. 1, the land 10 will cut oil the flow of fluidunder pressure from the pump to the chamber 42, and will vent thechamber 42 to the pipe 11, whereupon the spring I will urge the valveelement l4 downwardly or inwardly, and tend to carry the :land l6 into aposition between the ports l9 and 2| and the land I5 between the ports23 and 26.

It will be understood, however, that even when the valve element I4 wasinits elevated position, during which it caused an advance or workingmovement of the ram or member i, the chamber 45 was at first incommunication with the pullback chamber 5 through the valve chamber 52,

the pipes II and 11 will be broken and the pipes H and 13 will be placedin communication with one another through the chamber 68 in the spacebetween the lands 69 and iii. The fluid under pressure from the pumpwill then be free to pass through the pipes 9 and 13, throughthe-chamber 68, thence through pipe H to chamber 42 where it exerts apressure on the inner end of the valve element l4 tending to shift itupwardly against the action' of the spring I1 and carry the land l6 intoa position between the ports 2| and 25 and the land l5 between the ports23 and I9. It will be understood that the piston 44 cannot go up at thistime because the head 46 in the chamber 45 limits such upward movement.

-When the valve element I4 is moved upwardly inFlg. 1, the land It iscarried into aposition in communication with .the chamber l3, and thusthe fluid under pressure from the pump 9 passes through the chamberl3and pipe 20 to the main cylinder 4. At the same time, the upwardmovement of the land l5 uncovers th port 23, and-this places ports 23and 26-in communication with one another through the lower part ofchamber", l3.

This places the pullback chamber 5 in =commuhication, through, the pipe22 and the lower part of chamber l3, withthe pipe 24 leading back to thereservoir, so that the fluid trapped in the pullback cylinder previouslyis now released'and is free to pass back to the reservoir. The workingmember then is free to descend because of gravity and such descentcreates a suction in the main chamber 4 and draws fluid fromthereservoir through pipe 21 and check valve 28. When the working memberor ram l encounters resistance, however,

oi! the valve element l4, however. moved the land l5 above the port 23,whereupon the chamber 5 was placed in communication, throughv the-pipes22 and 24, with the reservoir, whereupon'the pressure in the pullbackchamber fell and immediately also the pressure in chamber 45. The spring'50 then forced the flange 46 downwardly and moved thepiston 44downwardly and away from the full line position shown in Fig. 1. Theplaten 59 in moving downwardly, however, released the rod 53 stop piston44 in its downward position clear of the valve element l4.. The element14, however,

remains in its elevated position by reason of the hydraulic pressurethereon in the'chamber'42.

As soon as pressure in the main chamber 4 be- 7 gins to build up, acorresponding pressure will also build up in the chamber 45 and whensufflcient to overcome the action of spring 50 will force the piston 44upwardly into the full line position shown in Fig. 1, but it will stillbe outof contact with the element l4 because the latter is it stopsfurther rapid descent, whereupon the valve element 32in check valve 28closes, but continued delivery of fluid from the pump through pipes 9and 20 to the main chamber 4 builds-pp pressure in the main chamber andforces oq'ntinued descent of the member I.

It will be noted that when the valve element 61 then stillheld-hydraulically in its elevated position.

At the end of the forward or working movement of the platen 59, thevalve element 61 is I to be returned to the position shown in full linesin Fig. 1, whereupon the release of pressure in the chamber 42 allowsthe spring ll to shift the valve element downwardly until it engages therull lineor intermediate position shown in Fig. 1,

the pipe 20 leading to the main chamber. 4 is connected .to the pipe 24and the reservoir, and con ment I4 will continue downwardly untilthe-land I8 is disposed between the ports I8 and 2| and the land I5v isdisposed between the ports 23 and 26. This places the pipe 8 fromthemump in communication with the pullback chamber 5 and connects thepipe 28 from the main chamber 4 to the return to the reservoir.

The pump then delivers operating fluid to the pullback chamber to returnthe working member or ram I and the platen to the elevated or retractedposition, and as the pressure'in the pullback chamber builds up, thesame pressure will be communicated through the pipe 33 to the pilotchamber 28 of the pilot valve 28 and forcibly open the check valve 32,so that liquid may not only escape from chamber 4 through the pipe 28and valve chamber I3 back to the reservoir, but also may directly passthrough pipe 21 and valve 28 back to the reservoir, which expedites thereturn of the platen.

The valve element 81 may of course be operated manually in bothdirections if desired, and inasmuch as it is a balanced valve it willremain in either position in which it is placed. A convenient means foroperating the valve 81 in one direction to start a downward movement ofthe platen, which would be to operate the valve element 81 from the fullto the dotted line position in Fig. 1 includes a bellcrank lever 18pivoted at 88 to a suitable support adjacent the one side of the'element81, one arm of the bell crank lever being connected by a link 8| to anarmature 82 of a solenoid 83, The solenoid 83 is connected to line wiresL and L with a switch 84 included in series-therein. The switch 84 is anormally open switch, and by closing it momentarily, the solenoid 83will be energized, drawing the armature 82 upwardly; Through the bellcrank lever 18, the armature will shift the valve element 81 to the leftin Fig. 1 from the full to the dotted line position. The valve element81 is operated in the opposite direction, either automatically throughthe activity or operation of the platen or manually, as may be desired,and mechanism suitable for accomplishing this result will now bedescribed;

A bell crank lever 85, similar to the lever 18, is disposed at theopposite end of the valve ele ment 81 for operating the latter intheother direction. The lever 85 is pivoted at 88 to a suitable part of theframe, and is connected through a link 81 to an armature 88 of asoleducting bar 95 carried by a small piston 88 which reciprocates in achamber 81.

The piston 98 has a reduced extension 88 extending through the closedend of the casing 88 which provides the chamber 81, and carryinganadjustable abutment I88. A helical compres sion spring I8I iscompressed between the abutment I88 and the casing 88 so as toyieldingly The chamber 91 at its inner or closed end is connected by apipe I82 tothe pipe 28 leading to the main chamber 4,so that the chamber8? will at all times be subject to the pressure in the main cylinder 4of the hydraulic motor or ram. During the working stroke, when the fluidpressure in the chamber 4 becomes 'suflicientiy great or exceeds apredetermined pressure, such pressure in the chamber 81 will besufficient to 1 overcome the sprin I8I and force the piston 88 noid 88.The solenoid 89 is also connected to the line wires L and L, butincluded in the connection to one of theseline wires is a suitablecontrolling switch mechanism. The line wire L is connected by awire 88to a normally open outwardly or downwardly and cause the contact bar 85to bridge contacts 83 and 84.

Thus the circuit through the solenoid 88 will be closed automaticallywhenever the pressure in the main chamber of the ram or hydraulic motorexceeds a predetermined pressure depending upon the resistance of thespring I8I, and as soon as the pressure in the main chamber 8 falls, thespring I8I will return the piston 98 to its elevated or retractedposition and open the circuit through the solenoid 88. This arrangementprovides for the automatic shifting of the valve element 81 into thefull line position of Fig. 1=to release the hydraulic holding pressureon the valve element I4 automatically after the pressure on the main ramhas exceeded the predetermined pressure.

The circuit through the solenoid 88 may also be closed automatically bydisposing an electric switch I 83in a position to be operated by theplaten at a selected point. in the latters travel, and this switch I83is connected in parallel across the wires 88 and 82 to the contacts ofswitch 8|. The switch I83 may have an operating arm I84 disposed in thepath of travel of a cam I85 on the platen 58, and the switch I83 may bemounted on the press frame in a position to be shifted in a directionalong the path of travel of the platen so that the point in the travelof the platen 58 at which the switch I83 will be operated to reverse thedirection of travel of the platen may be varied.

In order that the action of the switch I83, and the pressure operatedswitch formed by contacts 83 "and 84 and 85, may be selectively renderedinoperative at will, a switch I 88 may be 'confrom the dotted to thefull line position of Fig. l.

Connected in parallel across the switch 9| is another switch including apair of contacts 83 and 84 which are arranged to be bridged .by-aconnected in series in the-wires I81 and I88 connecting the switch. I83to the wires 88 and 82 respectively, and a switch I88 maybe connected inthe wire II8 which connects the wire 88 to the contact 84. The contact93 is connected to one side of the switch 8| by a wire III. The valveelement 81 may be, returned to its normal position shown in Fig. l byoperation of the button 8|, which is a selective manual control, or bythe pressure responsive device which bridges contacts 83 and 84 by thebar 85, or by the operation of the position responsive switch I83.

The button at also functions its a may button :of dies. As soon as thehandle '49 is released it is returned to the neutral position and thevalve element l4 in then under the control or the auxilia y valve 68. h

In the operation of the press with this system, when one, desires tostart a forward or-downward movement of the platen 59, one merelypresses the button 84 which causes a movement of the valve element 61from the full to the dotted line position in. Fig. 1. This causes ahydraulic actuation of the valve element [4 into its upper .positionwhere it initiates -a forward movement of the main ram I. This forwardmovement is stopped either by a manual operation of the button 9|, bythe position responsive switch I03 when the cam I engages and operatesthe switch arm I04, or by 'the pressure on the main ram or work which,when it reaches a predetermined pressure, forces the piston 96 outwardlyand closes the circuit between the contacts 93 and 94. The operation, ofthe solenoid 89 through any of these three switches causes a returnmovement of the valve element Ii! to the full'line position of Fig. 1and the parts return to their normal retracted positions.

It should be noted that when the platen 59 has nearly reached its upperlimit'of movement, as

determined by its engagement with the collar 60,

it shifts the valve element 53 upwardly and breaks the connectionbetween the chamber 45 and the main'ramchamber 4, and establishescommunication between the chamber 45 and the pullback chamber 5. At thistime th pressure in the pullbackchamber 5 is communicated to the chamber45 which forces the piston 44 upwardly, and thus forcibly holds thevalve element l4 in the intermediate position shown in full lines inFig. 1 and this establishes the normal idle condition of the press,which remains until a new operation is started by a closing of theswitch 84. When in this position the pump is by-passing at no pressurethrough pipe 9, port l9, around land IGthrough port 2|, and through theport to pipes 24 and ill to reservoir 1.

Referring now to Fig. 2, a slight modification of the system shown inFig. 1 has been illustrated. The system is substantially the same as inFig. 1

except that the spring I1 is omitted and in place thereof the valveelement l4 extends through a.

cha er l|2 which is preferably smaller than andseparate from thechamber[3. Within the chamber H2 the valveelement l4 carries'a piston flange orcollar I I3 fitting the side walls of chamber 2. A pipe Il4 is connectedto the upper end of the chamber H2 and also to a port 'I I5 in-the valvechamber 68 of the valve 68. The port H5 is disposed between the ports 16and I4 and between the lands 69 and I8 when the valve element 61 is inthe full line position shown in Fig. 1. Thus when the valve element 61is'in its normal or idle position shown in full lines in Figs. 1 and 2,the pipe 13 from thepump will deliver fluid under pressure through thepipe I I4 to the chamber H2 and hydraulically urge the piston flange H3downwardly and through it urge the valve element I4 downwardlyv in thesame manner as the spring II. The chamber 2 and the head or flange 3 aresufficiently small,

. however, so that the pressure thereof can be overcome by the pressurein the chamber 45.

Thus the only difference between the embodi-' -ment shown in Fig. 2 andthat shown in Fig. l

is the replacement of the spring I! with the hydraulib pressure throughthe chamber ll2',- and the control of that pressure by the auxiliary oractivities valve 66. The operation otherwise the same as in Fig. 1.

It will be noted that the pump a, in both Figs.

., 1 and 2, may be of the type which automatically sets itself toneutral delivery position to. maintain' a predetermined pressure in thepipe 9, a pipe I 16 being connected for this purpose between the pipe 9and the small piston chamber III of pressure, as is well known in theart.

In the embodiment of th invention shown in Fig. 3, the system is thesame as in Figs. 1 and 2, except that instead of havingv electrical'circuits controlling the solenoid 89 which operates the valve element61 back into its normal full line position of Fig. 1, a pressureresponsive piston 96a is disposed in alignment with and adiacent one endof the valve element 61 so as to force the latter to theright in Fig. 1,into its normal return and idle position. The piston 98a corresponds tothe piston 98 of Fig. l, and its chamber is connected to the pipe 2|!leading to -the main cylinder 4 through the pipe I02, as in 'to passfluid from the chamber 91 and. which closes automaticallyto preventreverse flow.

Connected in parallel across the check valve H8 is a pressure reliefvalve H9 which maybe of any well known type, and which is pressureclosed but which opens to pass fluid from the pipe 12- towards thepiston chamber 91. Thus fluid will flow from the pipes 20 and I02 tothe. pressure responsive piston chamberv 91. only after the pressurebuilt up in the pipe 20 is suflicient to unseat the spring or'pressure'closed valve element of valve 9. In such a case the spring or resistancepressurein the valve H9 will beset for an amount greater than that forwhich the spring I0! is setso that as soon as the valve 9 opens, thepressure then created'in chamber 91 will immediately cause a relativelyrapid movement of the piston 96a and a prompt movement of the .valveelement 61, so as to prevent wire drawing in the activities valve 86.The check valve 8 permits free escape of the actuating fluid from thechamber. 91 as soon as the pressure in the pipe 20 and chamber 4 falls.

In the embodiment of the" vention shown in Figs. 1 to 3, it will benoted that the main controlling element is the valve element of'the mainreversing valve. It is hydraulically operated into and held in'oneposition, and yieldingly urged into the other position by spring orhydraulie means, so that the controlling element may be said to behydraulically operated and controlled.

It will also be noted that this hydraulic holding of the reversing valveelement maybe discontinned or interrupted to change the direction ofmovement of the working member, by means responsive switch or devicewhich is responsive to the pressure of the working member on the work,or the resistance encountered by the working member. Another of suchmeans is the position responsive switch which is disposed in a positionto be operated by the platen when the platen reaches a predeterminedpoint in its movement,

and which position may be adjusted by shiftingof the position operatedswitch along the path of travel of the platen. Either or both of thesemeans may be rendered effective or ineffective as desired, and I havealso provided the safety switch which may be operated at any point inthe travel of the platen to cause an immediate reversal of the motor. Insome instances it may be desirable to stop the press ram on its returnstroke at some intermediate position, and to make this possible thecollar 60 is made adjustable into diiferent positions along the rod 53.Thus the point at which the ram is brought to rest and the. pump set foridle delivery at substantially no pressure, may be varied by shiftingcollar 60 along rod 53.

In the modifications of the invention shown in Figs. 4 to 6, those partswhich correspond to similar parts in Figs. 1 to 3 are given similarreference characters and will not be again specifically described. Thesemodifications are similar to the system shown in Fig. 1, except that thereversal of the press at the end of the working stroke is responsive toa time interval after the forward working stroke is started, instead ofbeing responsive to the working pressure or platen position. In thesystem as modified in the manner shown in Fig. 4, the pressureresponsive switch, the switch operated by the platen, and the solenoid89 and bell crank lever 85 are omitted. Instead, a helical compressionspring I is disposed in the chamber 68, under compression between oneend of the chamber and the land I0. This spring I20 yieldingly urges thevalve element 01 to the right whenever the valve element is released.

The solenoid 83 is supplied with current from line wires L and L as inFigs. 1 and 2, but the circuit of the solenoid 83 iscontrolled by anormally closed switch I2I and a time switch I22. This time switch I22is in series with the switch IN and when idle opens 'the circuit to thesolenoid 83. When the operating or control button I23 of the time switchI22 is operated, the time switch closes the circuit to the solenoid 83and keeps its closed for a predetermined interval of time and thenautomatically opens it. The switch I2I is merely a safety switch whichmay be operated to open the circuit and deenergize solenoid 83 when onedesires to reverse the travel of the press before the time interval forwhich the time switch is set, has been completed. Thus, to start thepress the attendant operates the button I23 to set the time switch intooperation and close the circuit to the solenoid 83.

The solenoid 83 when energized, operates the valve element 61 to theleft into the dotted line position of Fig. 4 against the action ofspring I20. This causes an advance of the press in the. same manner asexplained in connection with Fig. 1, except that the solenoid 83 remainsenergized to hold the valve element 61 in the dotted line until the endof a predetermined interval of time, whereupon the circuit is openedautomatically; The spring I20 then shift the valve element 61 to theright to cause a return of the platen to the normal, retracted position.The

travel of the'platen is thus automatically reversed after the lapse of apredetermined interval of time, regardless, of the position of theplaten or the pressure developed on the working member, but if the pump6 is of the type which automatically sets itself to neutral ornon-delivery position when a predetermined pressure has been reached,the press could move into pressing position, build up a selectedpressure, and maintain I it until the lapse of the predeterminedinterval of time, whereupon the platen would be automatically retracted.4

The time switches of the types which will. per- .form such a functionare common articles of commerce, and per se form no part of the presentinvention. One type of switch which may be adapted ctor thi purpose isknown as a Microfiex" timer switch manufactured under U. S. Patents Nos.1,383,533, 1,460,707 and 1,794,762, to which reference may be had forfurther information. Similar time switches which may be used to performthe same function are, for example, those which have also been employedas circuit controlling timers for vehicle direction signals. Examples ofthese are found in U. S. Patents Nos. 1,672,791 and 2,001,266.

In Fig. 5, the valve 66 is substantially the same as in Fig. 1, and itselement 61 is shifted in opposite directions by the solenoids 83 and 88operating through the bell cranks 19 and 85. The solenoid 83 is suppliedwith current from the line wires L and L and this circuit is controlledby a normally open switch I24. The operating part of the switch I24 alsopreferably operates the stem I25 of a time switch I26 which may besimilar to the switch I22 of Fig. 4, except that the circuit throughswitch I26 is normally closed, but when the switch I26 is operated, itopens the circuit therethrough and holds it open for a selected timeintervaL-then recloses it automatically; The time switch I26 is includedin series with the solenoid 89 which operates the valve element 67 tothe right of Fig. 5, and the solenoid 89 is supplied with current fromline wires L and L The time switch I26 is connected by a wire I2'I tothe line wire L and the other side of switch I26 is connect-ed by a wireI28 to one side of the solenoid 89. The other side of solenoid 89 isconnected by a wire I20 to a contact I30 of a suitable switch, the othercontact I3I of which is connected by a wire I32 to the other line wireL.

A wiper blade I33 is arranged to bridge the contacts I30 and I3I andcomplete a circuit therethrough under conditions which will be explainedpresently. The wiper blade I33 is carried by a lever I34 which ispivoted at I35, and which has a forked end thatloosely straddles acollar I36 provided on the valve element 61 exteriorly of the valvecasing 68. When the solenoid 83 is energized and the valve element 6'!is shifted to the left in Fig. 5, the collar I36 will engage one arm ofthe forked end of lever I35 and rock the lever in a manner to shift thewiper I33 across the contacts I30 and I 3I as' the valve element 61reaches its dotted line position in Fig. 5. This completes a circuitthrough the solenoid 89 except as controlled by the time switch I26. Thevalve element 61, being balanced, will remain in that position and willhold the wiper blade I33 across the contacts I30 and I3I.

To start an operation of the press with this modification, the attendantcloses switch I24 'to energize solenoid 83, and this causes a shiftingof the valve element 61 from the full line to the dotted line positionof Fig. 5. At the same time that the switch I24 is closed, the stem I25is operated to start an operation of the time switch I26 whichimmediately opens the circuit between the wires I21 and- I28 leading tothe solenoid 89. Since the time witch I26 is set in operation before orsimultaneously with the movement of the valve element 61 into the.dotted line position, the circuit through the solenoid 89 will beopened at the time switch I26 before or simultaneously with the closingof the circuit across the contacts I30 and IN, so. that the solenoid 89will remain deenergized. The switch I24 may be immediately reopened orit may remain closed until the time switch completes its period of time,but after the lapse of a predetermined interval of time, which of coursemay be adjustable the same as that for the time switch I22, the timeswitch I26 will complete a circuit'between the wires I21 and I28 andthus complete an energization of the solenoid 89. This solenoid 88 thenoperates the valve eleswitch I24 can cause a movement of the valveelement 61 to the left to start a new advance of the platen. Connectedacross the wires I21 and I28 is a normally open switch I31 whichoperates as a safety switch. The time switch I26 should preferably havesome optional or selective provision by which it .may be returnedquickly to starting position 'without'waiting for the lapse of time, sothat after the platen has been started on an advancing movement it couldbe reversed as a safety measure.

Unless the switch I26 is provided with such a selective release andreturn, the switch I31 should be used, and since it is a normally openswitch, its closing causes energization of .the

solenoid 89 and a reversal of the platen. In 81.11011 a case thesolenoid 89 shouldv be more powerful than the solenoid 83, so that itmay force the valve element 61 to the right against the action of thesolenoid 83. The switch I31, if used,.is preferably of the reset type sothat when closed it will remain closed and keep the valve element 61 inthe full line position until the switch I24 is opened, after which theswitch I31 is manually reset to open position. If the switch I24 is ofthe type which immediately opens without waiting for the control stemI25 of the time switch to return to normal position and open I intothree positions,in one end position of which the circuit of' solenoid83, then theswitch'l31' may be merly a normally open switch without thereset feature, because then a momentary closing of the solenoid 89 wouldbe all that would be necessary to cause 'areturn of the platen.

In Fig. 6, the arrangement is the same as explained for Fig. 5, exceptthat the circuit of solenoid 89, instead of be ngbontrolled by the leverI34 and contacts I30, I3I v.andi I33, is controlled-:by a switch I38which is included in series with the solenoid 89. The switch I38 is anormally closed type but is opened when the switch arm I39 thereof isoperated by a cam I40 provided on the platen as the platen approaches orreaches its upper limit of movement.

Thus the solenoid 89 could remain energized to hold the valve element 61to the* right'or'full platen.

line position until the. platen completed any ar-t or all of its returnstroke, at which time the cam I40 would engage and operates'witch armI39 and open the circuit at the switch I38, and keep it open, and thusdee'nergize the solenoid 89.-

ciently long so that the'switch arm I30 may be engaged and operated toopen the switclf- I38 soon after the platen starts its return stroke,

and to keep it open until the platen has again advanced approximately toits full extent. The

operation is otherwise the same as in Fig. 5.

It will be understood that various changes in the details andarrangements of parts, which have been herein described and illustratedin order to explain the nature of the invention,

may be made by those skilled in the art within the principle and scopeof the invention, asexcylinder connected to said member for operating ittoward and from work, and pipes connecting the pump and cylinders toform ahydraulic circuit, a controlling valve connected to said fluidactuated means in said pipes for causing an adv member and having avalve element operable it causes delivery of actuating fluid to the maincylinder and opens the pull-back cylinder for escape of actuating fluid,and in another end position of which it connects the actuating fluid tothe pull back cylinder and opens the main connections to said pump tocreate a desirable J minimum back pressure on the pump, hydraulic meanssupplied directly from said pump before said choke for urging said valveelement into one ofsaid end positions and holding it there, hydraulicmeans also connected to said pump before saidchoke and also operable onsaid valve element for forcibly actuating said valve element, into theother of said end positions, and holding it there, an auxiliary valvefor rendering both of said hydraulic means alternately effective on saidelement to determine the direction of 7 travel of ,said working member,a fluid operated device for overcoming the pressure of one of saidhydraulic meansand forcing said element into said intermedate positionto stop the actuation pull-back cylinder and while out of said zone forconnecting saiddevice to said main cylinder.

2. In a hydraulic motor, a working member,

fluid actuated means including a continuously vance, a return or a,stopping of said member and having a valve element operable intothreeThe cam surface I40 may be made sufllce, 9, return or a stopping of saiddelivery of actuating fluid to the main cylinder and opens the pull-backcylinder for escape of actuating fluid, and in another end position ofwhich it connects the actuating fluid to the pullback cylinder and opensthe main cylinder for both cylinders, a choke in said pipe connectionsto said pump to create a desirable minimum back pressure on the pump,hydraulic means supplied directly from said pump before said choke forurging said valve element into one of said" end positions, and holdingit there, hydraulic means also connected to said pump before said chokeand also operable on. said valve element for forcibly actuating saidvalve element into the other of said end postions and holding it there,an auxiliary valve for rendering both of said hydraulic meansalternately effective on said element to'determine the direction oftravel of said working member, a hydraulic device operable on said valveelement to shift it from said other position into said intermediateposition against the action of said urging means, and means controlledby said working member at a desired point in its return movement forconnecting said pull-back cylinder to said hydraulic device and by thepressure of fluid from the pull-back cylinder operating said valveelement into said intermediate position .and holding it in that positionafter the valve element reaches said intermediate position.

3. An improved operating system for a hydraulic motor of the type havinga working member, hydraulic means for advancing said member, hydraulicmeans for retracting said member, and a source of operating fluid underpressure, which comprises the combination therewith of a main valvehaving a chamber, and a valve element movable back and forth in saidchamber along a selected path, said element having lands spaced apart ina direction along said path, said casing having ports connected ingroups by the spaces between said lands and covered and uncovered by thelands as they pass, one of said ports being connected to said advancingmeans, another to,

said retracting means, another disposed between these two and connectedto said source, others beyond both of said first two ports and connectedto exhaust, means operable on said element and urging it yieldingly intoone end position in which 3,867,941 positions, in one end position ofwhich it causes,

meansior moving said element into the opposite end position in which itconnects said source to said advancing means and said retracting-meansto exhaust and holds saidelement releasably in that end position solelyby a continuance of the fluid moving pressure on said element untilrelease of said element is desired, a valve controlling the activity ofsaid fluid actuated means, and unbiased into any'of its positions, meansfor moving said last mentioned valve in a manner to admit fluid to saidfluid actuated means to cause movement of said element into saidopposite end position, and additional and separate means responsive' toa selected operation of said motor for operating said last mentionedvalve in a manner to cause release of actuating fluid from said elementthrough said fluid actuated means.

4. An improved operating system for a hydraulic motor of the type havinga working member, hydraulic means for advancing said member, hydraulicmeans for retracting said member, and a source oi operating fluid underpressure, which comprises the combination therewith of a main valvehaving a chamber, and a valve element movable back and forth in saidchamber along a selected path, said element having lands spaced apart ina direction along said path, said casing having ports connected ingroups by thespaces between said lands and covered and uncovered by thelands as they pass, one of said ports being connected to said advancingmeans, another to said retracting means, another disposed between thesetwo and connected to said source, others beyond both of said first twoports and connected to exhaust, means operable on said element andurging it yieldingly into one end position in which it connects saidretracting means to said source and said advancing means to exhaust, andholding it yieldingly in that position, a hydraulic device having apiston normally inoperative to opposemovement of said element into saidone end position, but movable under hydraulic pressure into a positionin which it releasably limits movementof said element under the actionof said it connects said retracting means tOsald source and saidadvancing means to exhaust,,and'holding it yieldingly in that position,a hydraulic device having a piston normally inoperative to opposemovement of said element into said one end position, but movable underhydraulic pressure into a position in whichit releasably limits movementof said element under the action of said urging means to an intennediateposition in urging means to an intermediate position in which a landcloses said port connected to said retracting means and said source portand said port connected to said advancing means are connected toexhaust, means including a valve controlled by said member and operableto connect said retracting means to said hydraulic device and cause saidmovement of said piston when said member is "retracted within a selectedextent and to connect said element releasably in that end positionsolely by'a continuance of fluid pressure on said element nected toexhaust, means including a valve controlled by said member and operableto connect said retracting means to said hydraulic device and cause saidmovement or said piston when said member is retracted within a selectedextent and to disconnect said retracting means from said hydraulicdevice when said member is away from said selected extent of retraction,fluid actuated moving means until release of said element is desired,whereby said element cannot be moved sure, a main valve connected tosaid source and ent successive positions in one of which positions itconnects said source to said advancing means and said retracting meansto exhaust to. cause an advance of said working member, in another ofwhich positions it connects said source to said retracting means andsaid advancing means to exhaust to cause a retraction of said member,and in a third, intermediate position in which it closes said retractingmeans against escape of operating fluid and connects said source andsaid advancing means to exhaust to cause said member to remainstationary, means for yieldingly urging said element into saidanotherposition, a hydraulic device operable into' one position in whichit directly prevents movement of said element by said urging meansbeyond said intermediate position and into another position in which itpermits movefree of bias into either position, means controlled by theposition of said member for connecting said hydraulic device to saidretracting means for operation of said device into its said one positionautomatically when said retracting means is under fluid pressure, andfor also connecting said device to said advancing means when saidworking member is being advanced, for operation into its said oneposition when fluid pressure on said ment of said element by said urgingmeans into said urging means into said oneposition to cause an advanceof said element, wpereby said element may be manually moved and heldmomentarily in said one position selectively, and means controlled bysaid working member for causing operation oi said hydraulic device intosaid one position -when said member is retracted to a selected extent,and into its other position when said member is away from its saidretracted extent. a

6. In a hydraulic motor system, a working member, hydraulic means foradvancing said member, hydraulic means for retracting said member, asource of operating fluid under presboth of said means to form therewitha hydraulic circuit for operating said member, said valve having acontrol element operable into three difierent successivepositions, inone of which positions it connects said source to said advancing meansand said retracting means to exhaust to cause an advance of said workingmember, in another of which positions" it connects said source to said,retracting means and said advancing means to exhaust to cause aretraction of said member, and

. in a third, intermediate position in which it closes said retractingmeansagainst escape of operating fluid and connects said source and saidadvanc-v 'said element into said another position, a hyadvancing meansis abov a predetermined pressure, means for operating said balancedvalve in a manner to cause admission of operating fluid to said elementoperating means, and additional means responsive to a selected operatingcondition of said system for moving said balanced valve in a.' manner torelease operating fluid from said element operating means.

'i. In a hydraulic motor system, a working member, hydraulic means foradvancing said member, hydraulic means for retracting said member, asource of operating fluid under pres sure, a'main valve connected tosaid source and both oi said meansto form therewith a hydraulic circuitfor operating said member, said valve having a control element operableinto three difierent successive positions, in one of which positions itconnects said source to said advancing means and said retracting meansto exhaust to-cause an advance of said working member, in another ofretracting means and said advancing means to exhaust to cause-aretraction of said member, and a third, intermediate position in whichit closes saidretracting means against escape of operating fluid andconnects said source and said advancing means to exhaust to "cause saidmember to remain stationary, means for yieldingly urging said elementinto said another position, a hydraulic devi'ce operable into oneposition in which it pre- 40}v entsmovement of said element by saidurging 'nieans-beyond said intermediate position and into an' otherposition in'which it permits movement not, said element by said urgingmeans into said sure, a main valve connected to said source and .jorcingit into-said one position to cause an adg other position for thatelement, fluid operated means selectively operable on said element foroperating pressure thereon after movement of said element has occurred,releasing it from that I one position by a release of fluid pressurethereon,

draulic device operable into one position in which it prevents movementof said elementby said urging means beyond said-intermediate positionand into another position in which it permits movement of said elementby said urging means into saidanother position for that element, fluidoperated means operable on said element for forcing it into, said oneposition to cause an advance of to said element operating means and itsrelease therefrom, said balanced valve being normally and meansincluding a valve operated by said member to place said deviceautomatically under the fluid pressure on said' retracting means whensaid member is within a predetermined zone of retraction, and under thefluid pressure on said advancing means when said outside of said zone. Vr

I 8. In a hydraulic -motor system, a working member, fluid actuatedmeans for advancing said member, fluid actuated means 'for retractingsaid member, a source of actuating fluid under pressure, a circuithaving a controllingvalve for causing actuation of said member bothadvance and retraction, said valve havi a controlelement movable intoany of thy e positions, in one of which it causes actuating fluidpressure on said member'advancingmeans, in another of which it causesactuating fluid pressure on said member retracting means, and in a thirdof which it is intermediate its other mentioned positions and closessaid member retracting means'against e'scape of actuating fluid,meansfor yieldingly urging said element into its said another position andholding it there, fluid operated means for overwhich positions itconnects said source to said member is disposed which it causesactuating fluid pressure. on said member advancing means, in another ofwhich it .causes actuating fluid pressure on said member retractingmeans, and in a third of which it is intermediate its other mentionedposition and closes said member retracting means against escape ofactuating fluid, means for yieldingly urging said element into, its saidanother position and holding it there, means operated by fluidpresmember during its travel for connecting said fluid operated deviceto the fluid pressure on said re-' tracting means when said member is inone zone of retraction, and breaking that connection and releasing saiddevice from the fluid pressure obtained from said retracting means whensaid member is outside said zone.

9. In a hydraulic motor system, a' working member, fluid actuated meansfor advancing said member, fluid actuated means for retracting saidmember, a source of actuating'fluid under pressure, a circuit having acontrolling valve for causing actuation of said member in both advanceand retraction, said valve having a control element 'movable into any01' three positions, in one of sure for operating said element into itssaid one position and holding it there by continuance of fluid pressure.a pressure balancedvalve for controlling vthe admission of fluid underpressure is and its release from said element operating means, a fluidoperated device efl'ective when operated by fluid pressure to mm saidelement from its said another position into said intermediate positionor limit movement of said element from its said one position past saidintermediate position, means including a valve operated automatically bysaid member during its travel for connecting said fluid operated devicealternately to the fluid pressures on said retracting means and saidad'- vancing means, depending upon the zone 01 movement in'which saidmember happens to be.

moms F. STACY.

